1. Technical Field
The present invention relates to an interface apparatus and a cascading method thereof, and more particularly to an interface apparatus that utilizes the Thunderbolt interface, a cascading system thereof and a cascading method thereof.
2. Description of Related Art
As the technology advancements and rapid changes of the computer functions, a wide variety of peripherals are emerging continually. For user's convenience to upgrade or to expand computer performance or function, the computer motherboards are usually equipped with AGP, PCI, PCI-E, and ISA slots for users to install a video card, a sound card, a network card, or other expansion cards. Furthermore, motherboards are also equipped with Firewire, USB, and other expansion interfaces for users to connect hard drives, printers, and other external devices.
Recently, Intel Corporation from United State has released a whole new Thunderbolt interface which integrates PCI Express and DisplayPort technologies together, so as to transmit data and video streaming through a single cable simultaneously. FIG. 1 is a diagram illustrating the data transmission of the Thunderbolt interface. Referring to FIG. 1, the Thunderbolt transmission technology provides two channels 122 and 124 on a cable 12 which are served as the PCI-E and the DisplayPort to transmit data and stream video respectively. Relying on the control of two Thunderbolt controllers 14 and 16 which are at two ends of the cable 12, the transmission rate of each channel may reach up to 10 Gb/s for both directions. This allows high speed data transmission between a computer and peripherals. The bandwidth provided by the Thunderbolt technology allows several high speed devices to be daisy chained without a hub or a switch.
For example, FIG. 2 is a conventional daisy-chain connection of the Thunderbolt interface architecture. Referring to FIG. 2, in order to implement a daisy chain cascading connection, a host 22, as a master terminal, requires a Thunderbolt interface port 222 and a Thunderbolt controller 224 supporting dual-channel transmission. The downstream cascaded Thunderbolt interface apparatuses 24, 26, and 28 are required to respectively equip two or more Thunderbolt interface ports 242, 244, 262, 264, 282, and 284. Since each of the Thunderbolt interfaces has 2 channels, the Thunderbolt controllers 246, 266, and 286 in the Thunderbolt interface apparatus 24, 26, and 28 are required to be configured to support four channel transmissions. Therefore, the production costs of the interface apparatus are increased.
However, two channels of the Thunderbolt interface are configured for data transmission and video streaming only, and Thunderbolt interface does not support channel aggregation, hence the transmission efficiency are limited. When the Thunderbolt apparatuses cascaded by the user do not include a display related device, the video streaming channel of the Thunderbolt device remains idle. In this case, the costly Thunderbolt interface port and controller can only supply half transmission efficiency, which is waste of resources. Furthermore, the daisy-chain architecture does not have a fault-tolerance function. When one Thunderbolt apparatus fails or malfunctions, all the downstream cascaded Thunderbolt apparatuses are disconnected as the daisy chain is broken, which may also result in data loss.